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  • 1
    Publication Date: 2021-06-22
    Description: A new set of cross-over marine data has been used to generate a regional model for the secular variation of the total geomagnetic field, showing the potential of the suggested approach for gaining a better knowledge of the field over oceanic regions. The model, which is valid for the Northern Atlantic region during the temporal interval 1960–2000, was obtained using spherical cap harmonic analysis (SCHA) in space and penalized splines in time. The maximum spatial expansion is equivalent to degree 9 in ordinary spherical harmonic analysis. Annual mean intensity data from different geomagnetic observatories have been used to improve the spatial and temporal resolution of the original dataset. Results indicate that the regional model improves, in terms of the root mean square error, the prediction given by the 11th generation of IGRF and CM4 global models, especially for the geomagnetic observatories considered. We also provide the uncertainty of the model coefficients and the secular variation prediction given by a bootstrap algorithm. The model is available in the EarthRef. org Digital Archive at http://earthref.org/ERDA/1728/.
    Description: Published
    Description: 21-31
    Description: 1A. Geomagnetismo e Paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: Geomagnetism ; Secular variation ; Regional modeling ; North Atlantic Ocean ; Spherical cap harmonic analysis ; Geomagnetic marine data ; 04. Solid Earth::04.05. Geomagnetism::04.05.02. Geomagnetic field variations and reversals ; 04. Solid Earth::04.05. Geomagnetism::04.05.03. Global and regional models ; 04. Solid Earth::04.05. Geomagnetism::04.05.04. Magnetic anomalies ; 04. Solid Earth::04.05. Geomagnetism::04.05.05. Main geomagnetic field ; 04. Solid Earth::04.05. Geomagnetism::04.05.08. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
    Publication Date: 2017-04-04
    Description: IN THE FILE
    Description: Published
    Description: 377-392
    Description: open
    Keywords: NONE ; 04. Solid Earth::04.05. Geomagnetism::04.05.03. Global and regional models
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
    Format: 879061 bytes
    Format: application/pdf
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  • 3
    Publication Date: 2017-04-04
    Description: The Spherical Cap Harmonic Analysis (SCHA) is a regional modeling technique based on appropriate functions which are solutions of Laplace’s equation over a constrained, cap-like region of the Earth. The concept was introduced in 1985 in the context of geomagnetism as a local or regional extension of the classic global spherical harmonic analysis. Starting from the basic principles in which the analysis method is founded, this paper describes the latest applications for the modeling of the main magnetic field and its secular variation. Although examples of applications over small areas will be given, it will be shown that, in general, the bigger the region the more appropriate the technique. Therefore, this paper focuses on the results and perspectives over continental areas, like Antarctica or Europe. The possible application to the derivation of isogonic charts for navigational purposes with suitable time predictions will be emphasized. At the same time, the limitations of the method will be examined. Although recent revisions of the technique seem to solve some of the problems, our present research focuses on the quest for solutions to the still unanswered questions.
    Description: Published
    Description: 291-307
    Description: 1.6. Osservazioni di geomagnetismo
    Description: 3.4. Geomagnetismo
    Description: 5.3. Banche dati di geomagnetismo, aeronomia, clima e ambiente
    Description: reserved
    Keywords: SCHA ; geomagnetic field modeling ; spherical harmonics ; declination ; 04. Solid Earth::04.05. Geomagnetism::04.05.03. Global and regional models ; 04. Solid Earth::04.05. Geomagnetism::04.05.05. Main geomagnetic field ; 04. Solid Earth::04.05. Geomagnetism::04.05.08. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 4
    Publication Date: 2017-04-04
    Description: The transformation of a set of spherical harmonic coefficients characterizing a model of the geomagnetic field, or a general function defined on a sphere, subject to a rotation of the coordinate system, is given by the direct relations between the coefficients and then by using a numerical approach. The parameters for a pair of such rotations (from one set to another, and vice versa) are given, along with a few examples of their application. The method is particularly useful for the comparison of geophysical characteristics derived from models developed under different coordinate systems. It offers a practical solution to the problem, which can be implemented without difficulty.
    Description: Published
    Description: 263-270
    Description: N/A or not JCR
    Description: reserved
    Keywords: geomagnetic field ; numerical techniques ; spherical harmonics ; 04. Solid Earth::04.05. Geomagnetism::04.05.03. Global and regional models ; 04. Solid Earth::04.05. Geomagnetism::04.05.05. Main geomagnetic field ; 05. General::05.05. Mathematical geophysics::05.05.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 5
    Publication Date: 2017-04-03
    Description: Lecter section of Physics of the Earth and Planetary Interiors 97 (1996)
    Description: Standard ways of building regional models of the geomagnetic field fail when one wishes to model secular variation (SV). The reason for this is that the SV is mainly a large-scale feature, while regional modelling is most appropriate for characterizing small-scale features. The new idea presented in this note consists in reducing this effect by requiring that the spatial derivatives of the SV produced by the regional model fit the values given by global (and smoother) models such as the international geomagnetic reference field.
    Description: Published
    Description: 15-21
    Description: N/A or not JCR
    Description: reserved
    Keywords: geomagnetic regional models ; secular variation ; 04. Solid Earth::04.05. Geomagnetism::04.05.03. Global and regional models ; 05. General::05.01. Computational geophysics::05.01.03. Inverse methods
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 6
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    Blackwell Science Ltd
    Publication Date: 2017-04-03
    Description: The method of spherical cap harmonic analysis (SCHA), due to Haines (1985) is appropriate for regional geomagnetic field modelling as it includes the required potential field constraints and, for a given number of model parameters, describes shorter wavelength features than a global spherical harmonic model. If the origin of the coordinate system is moved from the centre of the Earth towards the surface then the Earth's surface is no longer equidistant from the origin. At the Earth's surface the minimum wavelength described by a SCH model in the new coordinate system is smaller at the centre of the region than at the edge. This method of translated origin spherical cap harmonic analysis (TOSCA) has been applied to regional field modelling for Italy. The method is able to take advantage of the dense distribution of data at the centre of region and the model effectively smooths towards the periphery. The performance of the TOSCA model is discussed in relation to a model derived using conventional SCHA.
    Description: Published
    Description: 253-263
    Description: N/A or not JCR
    Description: reserved
    Keywords: ground and satellite data analysis ; regional field modelling ; spherical cap harmonic analysis ; 04. Solid Earth::04.05. Geomagnetism::04.05.03. Global and regional models ; 05. General::05.05. Mathematical geophysics::05.05.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 7
    Publication Date: 2017-04-04
    Description: The magnetic observatory deployed at DomeC, Antarctica, in the French-Italian base known as Concordia has now been permanently running for more than three years. This paper focuses on these long-term results which are more relevant for an observatory intended to provide absolute values of the field. The problems which emerged in this fairly long record are discussed and solutions suggested to upgrade the observatory to the standards of an absolute one (i.e. Intermagnet standards).
    Description: Published
    Description: 15-26
    Description: 1.6. Osservazioni di geomagnetismo
    Description: 3.4. Geomagnetismo
    Description: JCR Journal
    Description: open
    Keywords: Antarctica ; Dome C ; magnetic observatory ; continuos records ; 04. Solid Earth::04.05. Geomagnetism::04.05.03. Global and regional models ; 04. Solid Earth::04.05. Geomagnetism::04.05.05. Main geomagnetic field ; 04. Solid Earth::04.05. Geomagnetism::04.05.08. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 8
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    Springer
    Publication Date: 2017-04-04
    Description: Monitoring the Earth's magnetic field is carried out by geomagnetic observatories all over the world. In Italy, the first observatory was founded in 1880, when Pietro Tacchini, the director of the Central Meteorological Institute (Ufficio Centrale di Meteorologia), launched an initiative to study the distribution of the Earth's magnetic field over the Italian territory.
    Description: Published
    Description: 733
    Description: 1.6. Osservazioni di geomagnetismo
    Description: 3.4. Geomagnetismo
    Description: 5.3. Banche dati di geomagnetismo, aeronomia, clima e ambiente
    Description: reserved
    Keywords: Earth's magnetic field ; Magnetic observatories ; Italy ; L'Aquila and Castello Tesino ; 01. Atmosphere::01.03. Magnetosphere::01.03.06. Instruments and techniques ; 04. Solid Earth::04.05. Geomagnetism::04.05.02. Geomagnetic field variations and reversals ; 04. Solid Earth::04.05. Geomagnetism::04.05.03. Global and regional models ; 04. Solid Earth::04.05. Geomagnetism::04.05.04. Magnetic anomalies ; 04. Solid Earth::04.05. Geomagnetism::04.05.08. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 9
    Publication Date: 2017-04-04
    Description: The magnetic observatory deployed at DomeC, Antarctica, in the French-Italian base known as Concordia base, is now permanently running for more than three years. This paper focuses on these long-term results which are more relevant for an observatory intended to provide absolute values of the field. The problems which came up in the light of this fairly long record are discussed and solutions suggested in order to upgrade the observatory to the standards of an absolute one (i.e. Intermagnet standards).
    Description: Submitted
    Description: 1.6. Osservazioni di geomagnetismo
    Description: 3.4. Geomagnetismo
    Description: 3.9. Fisica della magnetosfera, ionosfera e meteorologia spaziale
    Description: JCR Journal
    Description: open
    Keywords: Geomagnetic observatory ; Antarctica ; 04. Solid Earth::04.05. Geomagnetism::04.05.03. Global and regional models ; 04. Solid Earth::04.05. Geomagnetism::04.05.04. Magnetic anomalies ; 04. Solid Earth::04.05. Geomagnetism::04.05.05. Main geomagnetic field
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: manuscript
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  • 10
    Publication Date: 2012-02-03
    Description: Spherical Cap Harmonic Analysis has been applied to obtain a reference model of geomagnetic secular change for Antarctica valid for the last forty years. In this paper, we use the latest available observatory data to update this model and to compare it with the 8th generation IGRF. In addition, the selected set of total field values used for the generation of the Oersted Initial Field Model have been employed together with observatory data to develop the first complete Antarctic Reference Model (ARM). This model improves the fit to the secular variation deduced from observatory data by about 60% relative to IGRF, and the fit to observatory and satellite field data by 8%. The model allows merging data sets taken at different altitudes and epochs in Antarctica, where significant temporal geomagnetic variations occur.
    Description: Published
    Description: 1192
    Description: JCR Journal
    Description: reserved
    Keywords: Geomagnetic reference fields ; Geomagnetic spatial variations (all harmonics and anomalies) ; Geomagnetic time variations - secular and long term ; 04. Solid Earth::04.05. Geomagnetism::04.05.03. Global and regional models ; 04. Solid Earth::04.05. Geomagnetism::04.05.04. Magnetic anomalies ; 04. Solid Earth::04.05. Geomagnetism::04.05.05. Main geomagnetic field
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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